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Solo 25m pool lengths underwater?

New Member

I wondered if you could advise me... I'm not freediving, but really enjoy doing laps at my local swimming pool underwater. I read some posts on here that concerned me about the risk of shallow water blackout.

I'm doing one 25m lap every 2 minutes for up to 50 minutes at a time. If I go fast, I'm 30s underwater, if slow and relaxed, 50s underwater. I've done this a few times with no problems.

Is this within safe limits, or am I in danger of shallow water blackout? Should I stop altogether?

I'm not trying to push any farther than that point and just plan to swim lengths because I like being underwater.

Well-Known Member

You are well within safe limits, assuming normal health and physiology. Roughly, given reasonable rest between dives, its pretty hard to get into blackout territory with dives of less than one minute. Much much more is possible with training.

Well-Known Member

Connor is right about the safe limits. It's possible to do repeat 50m with 15 seconds recovery and not become hypoxic. 25 m can be done as long as you can tolerate the urge to breath with 1-2 breaths between each lap and be fine.

That being said, it's absolutely never ok to do breathholding activities on your own. Partly because you never know if it when something will happen. If you go by statistics i could say that I've done at least 1000 dives between the depths of 10 and 65m and never had a blackout or loss of motor control. Does that mean I have 0% chance of blacking out and don't need a safety diver? NOT AT ALL. Anything can happen on any day. Remember that life guards dont count as safety either, once they get used to someone holding their breath they won't think twice about you lying motionless if your blacked out.

The other issue is the image it gives our sport. It's hard enough to get access to pools to freedive in, and if people start doing solo training it creates a bad image of recklessness for people who want to train properly with a safety diver watching them.

Well-Known Member

Now here is a place where reasonable people can differ and the details of each situation matter. I'm presently in a situation with no buddy. I don't push things at all and the life guards (who are truly worthless as safeties ) don't think I go more than 25 yards per dive. Once upon a good time I had a trained buddy and reasonable life guards and was going far far beyond 25 yards. Today I cooperate with the guards, mostly, and have figured out how to train effectively using both wet and dry. If I did not train alone, I could not train. I'm confident that BO risk in what I'm doing is zero. Other things the guards are trained to handle. Nathan's point about freediving alone is generally right on, but not always a reasonable option. In my case, I'm pretty sure I'm covered for pool training. Every diver needs to do the same.

Nathan's point about image is well taken. The primary reason I'm limited to 25 yrds is because of abuse by other, untrained divers. If you want to train freediving in a guarded pool, you have to work with the guards, show them that you are responsible, and understand their viewpoint.

New Member

Thanks very much for your replies. It's more a case of how I like to go swimming than practicing for freediving, I just love the relaxation of going underwater.

Am I right in thinking we just don't know enough about swimming underwater to say what I'm doing is absolutely safe yet? Like in 25 yrs given some good study we could say yeah that's fine, but right now no-one really knows?

Or more like don't make underwater swimming look cool or everyone will be dying trying to do it?

New Member

If you go by statistics i could say that I've done at least 1000 dives between the depths of 10 and 65m and never had a blackout or loss of motor control. Does that mean I have 0% chance of blacking out and don't need a safety diver? NOT AT ALL.

I'm a healthy fit 33yr old. With modern science, do we know that If I'm taking 50s to swim underwater for 25m then resting for 70s and doing it again 20 times there is 0% chance of shallow water blackout?

I'd happily enough swim 12.5m in 30sec with 30sec gap if that's safer... just don't want to cool down too much while resting

Please note I'm not trying to increase my times or train. I'm just bored of doing surface laps...

Well-Known Member

Shallow water blackouts are caused by suddenly drops of ppO2 during deep ascents. Hypoxic blackouts ( the only kind in the pool) are from steady drops in overall O2.

Truth be told no one in the world is going to black out from dropping O2 during 50s apneas. This doesn't mean that nothing else will happen and that you'll be fine 100% of the time. It's irresponsible to dive solo, no matter how easy what you are doing seems, especially in a public pool. If you have your own private pool you can do what you want if you're ok with the risks.

Well-Known Member

My advice was don't dive solo. The suggestion to use your own pool, not a privately owned pool, was to hide your stupidity from the public and not contribute to the negative image that some people have of our sport.

Well-Known Member

Johning, you said "I'm doing one 25m lap every 2 minutes..." It's good that you are resting between laps. The rest period after each lap is important for the type of thing you are doing - you need to clear any lactic acid build up and restore your O2 . I suppose 2 minutes is enough - but certainly don't be trying to shorten that period. Don't be fooled by being able to catch your breath rather quickly - you can feel rested yet still have lactic acid in your system - it needs a little longer to clear. Only you can know how you are feeling. If you feel dizzy, have tunnel vision, cramps, or otherwise are really struggling, then you need to back off a bit. But if you feel clear headed and fine after each lap then you are probably OK. Incidentally, I do this same type of underwater swim purely for pleasure - just staying down until the first discomfort appears, then back to the top to rest. Repeat.

New Member

I do something similar at my local pool, I use the lap lanes and just do 25m laps on a really slow pace with rests between (my watch displays my heart rate so I usually wait until I'm below 70-80 BPM rather than a specific time interval) so I'm just sort of cruising across the bottom, I find this to be very meditative and help me get comfortable with the different sensations.
I've also been using our ~4m (14ft) dive tank to practice equalizing and getting comfortable with the sensation of compression. Is doing >0:45 second dives at this depth dangerous if I'm not with someone actively spotting me? Because I'm nervous about SWB I don't push it, just wondering if I should be taking extra precautions? Thank you!
I'm firmly with cdavis on this one, if I didn't train alone I wouldn't be able to at all!

Well-Known Member

With 45 second dives and any half way reasonable rest period, you have zero chance of a low 02 blackout. Nathan has a very good point that lots of other things can get you in trouble.

My advice is get to know the lifeguards, explain what you are doing and don't stop moving. That helps them a lot. If you CAREFULY train exhale dives in 4m, you can simulate very deep dives. Just take it very slowly. Squeeze can come on very fast and with little warning.

New Member

Thank you for getting back to me so quickly! I am not in the habit of laying still at any point in my dive, I am always either finning or at least facing the surface so I can move my arms and check if anyone is swimming above me before I surface.
It was actually pretty comical during my training session today because our pool has several different groups and classes using the various areas at any given time without necessarily being on the schedule. Anyways, there is a group of ladies doing some aerobics in the deep tank wearing those float belts. Myself, being on limited time before work decided to say screw it and just continue my diving while swimming underneath them. I figured a 5 foot tall woman floating in 14 feet of water leaves about 9 feet of usable space underneath for me to hang out. So as I'm going under on my last dive I swam straight down the wall, up the drop off slope, and then down and out the first lane. When I finally popped up on the other side by the stairs I hear giggles and a couple of cheers from said group of ladies. Thankfully, the morning crew seems pretty relaxed.

Long story short, when you have on bright white fins and are female there are eyes on you lol! But our pool is mostly at your own risk so thankfully I don't have to deal with any micromanaging.

I have not trained any sort of exhale diving but I have done some buoyancy experimenting in the past in a similar dive tank (~3.6m) by allowing myself to sink naturally by exhaling at the surface. Keeping empty lungs all the way to the bottom was never uncomfortable for me, it was the first inhale upon surfacing that felt mildly painful (due to the sharp expansion/break of suction I think). Thankfully I think my thoracic cavity is pretty flexible (singing, dance, yoga, and swimming from young age) and I learned to frenzel equalize (surprisingly!) pretty naturally without thinking about it too much (think TOO MANY childhood plane trips).
Now I will say that when I am doing these 4m dives I have about 1.3kg on my waist to help me level out and maintain a more relaxed descent, and I know that being weighted increases the risk of any situation. I feel comfortable enough at my ability to take that risk (my belt also has a clip that can be released quickly) and make sure that I'm learning with correct technique but I am wondering if there are any considerations I should take with that out there? That's why I limit my dives to >:45 secs even though I can go for much longer comfortably.

Member

I do 25m dynamics (using small rubber pool fins). I take 4-5 recovery breaths between each lap. This is sustained for 30-45 minutes. Is this being stupid? This is done solo (there are usually regular swimmers sharing the lane with me, or at least in the lane next to me and life guards)

I've been debating getting a training partner, because it attracts more attention to what you are doing and more likely for the guards to ban you from the pool (this has happened to me in the past)